My invention relates to a video recording and reproducing apparatus such as that commonly known as the video tape recorder or deck for use with a magnetic tape cassette. More specifically, my invention pertains to means in such an apparatus whereby the screen of the associated display can be split into two windows or sections for the simultaneous presentation of different images.
Video tape recorders for use with magnetic tape cassettes have won commercial acceptance on a large scale. They record picture information in the form of a succession of frames of a composite picture signal on the tape cassette. The composite picture signal is a combination of the picture signal with horizontal and vertical synchronizing (sync) pulses and other information needed for reproduction and visual presentation of the picture signal.
It has been known to replace desired part of each frame of the prerecorded composite picture signal with some other picture information, so that the resulting presentation on a display is split into two windows or regions showing different images. The usual conventional practice for this split-screen presentation of different images has been to combine the outputs from two separate video tape recorders, or from one video tape recorder and one video camera, by use of very complex equipment. The composite picture signal resulting from the combination of the outputs from the two sources has then been recorded by an additional video tape recorder.
I object to this conventional practice as it involves the use of two or three video tape recorders, possibly plus a video camera or the like, and of the equipment for combining the outputs from two separate sources. Furthermore, since different devices are used for providing the video outputs to be combined and for recording the combined signals, such defects have been practically unavoidable as jitter and deteriorations in signal-to-noise ratio and frequency characteristic.
Japanese Unexamined Patent Publication No. 59-113580, laid open to public inspection on Jun. 30, 1984, represents a known attempt to solve the problem. It suggests a video tape recorder having provisions for accepting substitute picture information from some other source and for recording it at part of each frame of the prerecorded composite picture signal on the tape. However, this prior application is silent on the subject of how to accurately erase desired parts of the signal on the tape and how to record substitute picture information on exact erased parts of the tape.